To make the performance of the wireless data card play maximally, it needs the cooperation of the data card management software at the personal computer (PC) side.
The process of identifying device ports in the Windows system is generally as follows, first, it is to create a device description table for the device, the table must comprise the device's product ID (PID) and the device enumerated port descriptions information, the format of the information must comply with the requirements of the interface description format in the Windows system. The port description information in the table must be accurate and unique in order to ensure that the application program can quickly and accurately judge whether the attribute of a port is the diagnostic port, the modem port, or the AT (Attention) port, and so on, according to the port description information.
Since the processing methods of the systems are different, the Linux system has no similar port processing mechanism of the Windows system, and the device port identification methods of the Windows system cannot work properly in the Linux system. That is why the data card device port identification method for the Linux system, namely, how to make the software at the PC side in the Linux system correctly identify the data card device, and to correctly distinguish the AT command control port and the Modem data port, came into being.